@misc{indiciaeaf74affb8e3d,
  title = {Regional topography, physiography, and geology of the Northern Great Plains},
  author = {William Richard Keefer},
  year = {1974},
  doi = {10.3133/ofr7450},
  url = {https://pubs.usgs.gov/publication/ofr7450},
  note = {Source identifier: ofr7450}
}